Projectile



Jan. 29, 1946.

C. A. MARTIN PROJECTILE Filed Feb. 20, 1942 m 9 y M Patented Jan. 29,1946 UNITED it STATES PATENT OFFICE 2,393,648 PROJEGTILE Carl A. Martin,Negaunee, Mich.

7 Application February 20, 1942, Serial No. 431,708 7 (01. 102-52)(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 757) 3 Claims.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes. without the payment to me ofany royalty thereon.

This invention relates to a projectile and more particularly to animproved form of armor piercing projectile and method of making thesame.

Modern armor plates which have proven to have the greatest protectivequalities are, as is well known, provided with an extremely hard face byany one of several processes. Examination of projectiles after impactwith such facehardened plates seems to show that the resistance topenetration of such plates is due to the fact that on impact there is atendency for the head of the projectile to be shattered or upset by theblow of impact, in the happening of either event losing its power ofpenetration. However, if the shape of the projectile can be maintainedand the body thereof kept intact until the hardened surface of the platehas been destroyed, there will generally be no difliculty in penetratingthe underlying layers of softer material.

Prior attempts to reach this end in practice have involved the provisionof a projectile having a head portion of such great hardness as toshatter the face of the plate. Attempts have been made by the provisionof soft nose caps in advance of the hardened head and by controlledlocal heat treatment of the body to further increase penetration.However, eiforts to control the zone hardness of armor piercingprojectiles of small caliber have not been successful as the small sizeof these projectiles precludes any effective variation in the heattreatment which is applied to the various zones of the projectile.

It is therefore an object of this invention to produce an armor piercingprojectile or core therefor which, even in the small and mediumcalibers, will have optimum physical characteristics in respect tohardness and strength of each increment.

It is a further object to provide a method of producing such projectileswhich will relieve critical shortages of strategic materials and whichwill release machine tools, such as the automatic screw machines, forother essential employment.

It is a further object to improve the economy and efiiciency with whichsuch projectiles may be produced.

The exact nature of the invention as well as other objects andadvantages thereof will clearly appear from a description of a preferredembodiment as shown in the accompanying drawing in which:

Figures 1, 2, and 3 are longitudinal sectional views of a projectileformed according to my invention and representing the products of thethree principal steps of the method.

Figures 4, 5, 6, 7 and 8 are longitudinal sectional views of aprojectile produced according to modifications of the method.

Figure 9 is a similar view of a modified form of projectile produced bya similar method.

Referring to the drawing by characters of ref erence there is shown inFig. 1 a die I having a shape complementary to that of the desiredprojectile and provided with a pair of cooperating punches 2 and 3.Mixtures of powdered alloys or of the relatively pure constituents ofthe alloys are added to the die in such a manner that they are arrangedin layers or strata along planes perpendicular to the long axis of thebullet. The metal powders used are chosen for the characteristics whichare to be desired in the projectile. For example the tip zone 4 may beof material on the order of a hard mineral carbide with a suitablebinder metal, While the head zone 5 is of a material which on alloyingwill produce a characteristically hard steel, and the base zone 6 is ofa material which will produce a less hard but characteristically toughsteel. As indicated in Fig. 2 the powdered mixtures are then subjectedto pressure, preferably from each end simultaneously, to obtain a bodyhaving sufiicient strength and cohesiveness to resist ordinary handling.To promote adhesion at this stage it may be necessary to add a bindinconstituent to the original mixtures.

The formed bullet may then be removed from the mold and subjected to asintering process the details of which are determined in'a known mannerby the materials being treated. Normally sintering will be done byradiated heat in closed boxes with sufiicient charcoal to combine withthe oxygen of the air and form a reducin atmosphere. The finished bulletshown in Fig. 3 will be physically homogeneous and the physicalproperties of the various strata will be in accordance with theproperties of the materials used therein; At the interfaces between thevarious strata there will be considerable difiusion and interalloyingbetween the layers thus avoiding any abrupt changes in characteristicswhich might weaken the structure.

The modifications shown in Figures 4 to 7 inclusive correspond to thestep shown in Fig. 2, previously described. ,7 The modifications consistin variations in the method of charging the die for the moldingoperation. In the form shown in Fig. 4 the addition of the mixturecomprising zone 4 was gradually stopped and at the same time thedelivery of the powdered mixture comprising zone 5 was graduallyincreased. A similar procedure resulted in a similar blending or gradualtransition between zones 5 and 6. By choice of the rates of addition ofthe powdered material it is possible to producea smooth variation incomposition so that hardness may. be made to vary decrementally from thetip while the toughness of the metal varies incrementally.

' ..-may be desirable.

In the forms shown in Figs. 5 to 7 each unit of the powdered compositionhas been introduced separately to the die and separately compressed. Theshapes of the punch faces used in compressing each unit of thecharges..may;be' variedias tions will be found in the fact that acomposite structure may thus be produced in which each of the alloycompositions retains its own identity andits. own physicalcharacteristics although asdesired to produce interfacialjunctionsofiany desired section, those shown being merely illustrativeof some of the possible variations. In

this way it is possible to carry a'core. oftougher? the application offinal pressure to form the pro- I jectile body ready for sintering.

The modified form of projectile shown-inFig. 9 is of a type which wouldbe particularly useful as an unjacketed-projectile and is provided witha soft nose ll] of powdered iron or other relatively soft material whichon 'impact', serves to assist in penetration by lessening the tendencyto ricochetand by supporting and lubricating the body duringpenetration. These functions are fulfilled in conventional. constructionbymeans of a jacket and point filler or by soft capswelded, brazed,soldered, or mechanically secured to the projectile body. Sucha'projectile might be provided with a rotating band or otherconventional rifling engaging, means.

It will be obvious that a projectile body may be thus formed in anydesired shape suitable for use directly or as a core for theconventional jacketed projectiles. titles of powdered materials" may becharged into thedies results in elimination of wastage of materials. Inthe typical projectile cores used at present ahigh percentage of metalis lost in turning the body in automatic screw machines from 'bar.stock. Such elimination of wastage results in increased economy ofcritical metals and the method is also economical in that a pressuremolding operation replaces precision, machining from bar steel.

It .is generally contemplated that the harder The fact that exact quan-.

sociated in a homogeneous body with materials of greatly differingcharacteristics.

vI-claim:

1.'A- homogeneous projectilebody comprising heat treated. stratifiedmixtures of compressed powdered metallic products, the noseof'said bodybeing relatively soft, the portion of said body adjacent the nose beingof great hardness, and the remainder of said body being decrementallyhard and incrementally tough and formed from a plural number ofcompositions, one of which is a heat treated ferrous metal of a highhardness and another of which is a heat treated ferrous metal of greattoughness.

2.. A homogeneous projectile body comprising a sintered compositestructure of mixtures of compressed metallic powders, the nose of saidbody comprising a relatively soft material, an armor piercing portioncomprising a mixture of a hard metal carbide and a binder metal in rearof said nose, and: a base portion comprising a material varyingdecrementally in hardness and incrementally in toughness from said armorpiercing portion, said base portion being formed from .a plural numberof compositions, one of which-is a heat treated ferrous metal of highhardness and another of which is a heat treated ferrous metal ofgreat'toughness.

3. A homogeneous projectile body comprising a nose portion of a;relatively soft metal, a hard armor piercing portion of amixture ofmetallic carbide and a binder metal behindsaid nose, and a-metallicbaseportion varying decrementally in hardness and incrementally in toughnessfrom said-armor piercing-portion, said metallic base portion beingformed" from a plural number of compositions, one of which is'a heattreated ferrous metal of a high hardness and another of which is a heattreated ferrous metal of great toughness the portions of said projectilebody being interfacially allowed with each other.

CARL -A. MARTIN.

